Anti-biofouling methods are known in the art. US2013/0048877, for instance, describes a system for anti-bio fouling a protected surface, comprising an ultraviolet light source configured to generate ultraviolet light; and an optical medium disposed proximate to the protected surface and coupled to receive the ultraviolet light, wherein the optical medium has a thickness direction perpendicular to the protected surface, wherein two orthogonal directions of the optical medium orthogonal to the thickness direction are parallel to the protected surface, wherein the optical medium is configured to provide a propagation path of the ultraviolet light such that the ultraviolet light travels within the optical medium in at least one of the two orthogonal directions orthogonal to the thickness direction, and such that, at points along a surface of the optical medium, respective portions of the ultraviolet light escape the optical medium.
In WO2007/107722A1 a method of significantly reducing marine fouling is taught, incorporating the use of light in the area around an underwater surface, to detract zoo plankton and salps. These marine organisms are generally nocturnal to avoid optical predators such as fish. As a result they will avoid bright areas. Lights can be provided in fenders around a boat or the like, which can direct light to the area around the underwater surface of the vessel. Alternatively lights could be positioned over the underwater surface. In addition, the underwater surface can be made reflective to increase the light levels around the vessel. In a further alternative, the underwater surface can be coated in a bio- or chemo-luminescent coating.
In JPS5675290A preventive devices against organic adhesion are provided all around a hull near the waterline. Each device is provided with an ultraviolet ray reflection member of a bent plate supported by wires or vertical rods and an ultraviolet radiator like an ultraviolet lamp fixed inside the reflection member via a holding member containing electric wires together with a transparent cover to cover the ultraviolet radiator. It is also provided with a base plate in one body with the ultraviolet ray reflection member, and stuck on a shell plate of the hull via a liner of a permanent magnet, soft rubber, or the like fixed on the base plate. In this construction, the radiation of ultraviolet rays near the waterline prevents the adhesion of bacterial slime on the outer surface of the hull effectively.